ISO14064 Greenhouse Gas

Release date：2021-05-20 author： click：

Greenhouse gas effect

The greenhouse effect of greenhouse gases is due to their ability to absorb infrared (a kind of thermal radiation). The ability of greenhouse gases to absorb infrared rays is determined by their molecular structure. There are non-polar covalent bonds and polar covalent bonds in the molecule. Molecules are also divided into polar molecules and non-polar molecules. The strength of the molecular polarity can be expressed by the dipole moment μ. Only vibrations with changing dipole moments can cause observable infrared absorption spectra. Molecules with dipole moments are infrared active; while molecular vibrations with Δμ=0 cannot produce infrared vibration absorption, they are non-infrared active. In other words, greenhouse gases are infrared active molecules with dipole moments, so they have the ability to absorb infrared and preserve infrared heat.

The main greenhouse gas in the atmosphere is water vapor (H2O). The greenhouse effect produced by water vapor accounts for about 60%-70% of the overall greenhouse effect, followed by carbon dioxide (CO₂), which accounts for about 26%, and the other is ozone ( O₃), methane (CH₄), nitrous oxide (N₂O), perfluorocarbons (PFCs), hydrofluorocarbons (HFCs), chlorofluorocarbons (HCFCs) and sulfur hexafluoride (SF6), etc.

Historical originedit

Before 1820, no one had asked how the earth obtained heat. It was in that year that Jean-Baptiste-Joseph Fourier (1768-1830, French mathematician and Egyptologist), after returning to France, he wore a coat all year Most of the time is spent on heat transfer research. He concluded that although the earth did reflect a lot of heat back into space, the atmosphere still blocked some of it and reflected it back to the surface of the earth. He likened this to a huge bell-shaped container with clouds and gas at its top, capable of retaining enough heat to make life possible. His paper "Overview of the Temperature of the Earth and Its Surface Space" was published in 1824. At that time, this paper was not regarded as his best work, and it was not remembered again until the end of the 19th century.

In fact, it is only because the infrared rays of the earth are absorbed by certain gases or compounds in the atmosphere around the earth in the process of radiation to space that eventually lead to a general rise in global temperature. Therefore, the functions of these gases are similar to those of greenhouse glass, and only the sun is allowed. Light enters, and prevents its reflection, and then achieves the effect of heat preservation and warming, so it is called greenhouse gas. These include not only the various oxides of water vapor, carbon dioxide, and nitrogen that were originally in the atmosphere, but also the hydrofluorocarbons (HFCs), hydrofluorides, perfluorides (PFCs), Sulfur fluoride (SF6), chlorofluoride (CFCs), etc. The heat absorption capacity of different types is also different. The heat absorption per molecule of methane is 21 times that of carbon dioxide, and the nitrogen oxide compound is higher, which is 270 times that of carbon dioxide. However, it is nothing compared to some man-made greenhouse gases. Hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs) have strong heat absorption capacity.

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